The subject matter disclosed herein relates generally to systems and methods for computed tomography (CT) imaging.
In CT imaging, an X-ray source may be rotated around an object of interest (e.g., a patient, organ of a patient) to obtain imaging information. The object of interest is injected with a contrast agent (e.g., radiocontrast agent, an ionic contrast agent, a barium sulfate contrast agent, a blood agent) to provide maximum contrast in the imaging information. X-rays emitted from the X-ray source, attenuated by the object of interest, may be collected or detected by a detector and used to reconstruct an image. The X-rays may be emitted during predetermined acquisition windows based on cardiac measurements of the object of interest, a method commonly referred to as “cardiac gating.”
Conventional cardiac gating technique are based on a user selected scan prescription before initiating the scan (e.g., injecting the contrast agent, begin acquiring imaging information), which defines pre-programmed rules for acquisition windows. For example, the user measures a heart rate or determines specific arrhythmia complexes based from initial cardiac measurements of the object of interest. The user uses one or more tables listing candidate scan prescriptions with corresponding heart rates or specific arrhythmia complexes. Based on the initial cardiac measurements and the one or more tables, the user selects an appropriate scan prescription.
However, once the scan prescription is selected the scan prescription cannot be changed during the scan reducing the success rate for the CT scan. For example, any changes to the cardiac behavior of the object of interest that is not pre-programmed within the scan prescription may result in blurred or invalid imaging information. Invalid imaging information may require additional CT scans for the object of interest resulting, which may be adverse to the health of the objection of interest, such as increased radiation exposure, increased chance of having an adverse reaction to the contrast agent, or the like. Thus, there is a need to adjust the scan prescription during the CT scan.